This invention relates to engines, and more particularly to hybrid pulse combustion turbine engines.
In a conventional gas turbine engine, combustion occurs in a continuous, near constant pressure (Brayton cycle), mode. Although present gas turbine engine combustors are relatively efficient, the thermodynamic benefit to cycle efficiency associated with performing the combustion operation at a higher time-averaged pressure has led to many efforts to improve combustion.
It has been proposed to improve thermodynamic efficiency by applying the more efficient combustion of near constant volume combustion pulse detonation engines (PDEs) to turbine engine combustors. In a generalized PDE, fuel and oxidizer (e.g., oxygen-containing gas such as air) are admitted to an elongate combustion chamber at an upstream inlet end, typically through an inlet valve as a mixture. Upon introduction of this charge, the valve is closed and an igniter is utilized to detonate the charge (either directly or through a deflagration to detonation transition). A detonation wave propagates toward the outlet at supersonic speed causing substantial combustion of the fuel/air mixture before the mixture can be substantially driven from the outlet. The result of the combustion is to rapidly elevate pressure within the chamber before substantial gas can escape inertially through the outlet. The effect of this inertial confinement is to produce near constant volume combustion.
U.S. Pat. No. 6,442,930, for example, suggests combustor use of PDE technology in addition to use as a thrust augmentor in engines with conventional combustors. Other pulsed combustors are shown in U.S. Pat. Nos. 6,886,325 and 6,901,738.